Figure 5

ERK1 knockdown and H1944 cell proliferation. a Transfection with ERK1 siRNA achieved 70–80% knockdown of ERK1 but also stimulated expression of ERK2. The bottom panel shows that the changes in ERK1 (open bars) and ERK2 (grey bars) lasted at least 72 h. b On the whole, transfection with ERK1 antisense constructs did not have a substantial effect on growth in four independent clones of PTHrP-positive cells or three clones of PTHrP negative cells. The formatting is similar to Figure 4, with line segments linking points from the same H1944 cell clone. ERK1 knockdown (closed, black bars in the bottom graph, panel b) resulted in a slight increase in cell number at 72 h compared to NTC siRNA treatment (open bars in panel b) in the PTHrP-positive cells. *P < 0.05 vs. control NTC siRNA by paired t test.